This invention relates to polyester oligomers and polyester polyol-based coating compositions cured with a conventional crosslinker.
Due to legislation in Europe and the United States, coatings industries are under pressure to reduce volatile organic compounds (VOC) in coatings formulations. Therefore, coating compositions are needed which have good physical properties and appearance, but which are inherently low in viscosity and require minimal dilution with solvents. The use of branched hydroxy-functional polyester derivatives prepared by ring-opening with narrow molecular weight distribution and accordingly low viscosity, in coatings, has been described in British Patent 1,528,802. However, application of these polyester oligomers in, say, automotive coatings require the presence of high Tg acrylic polyols to get enough physical drying of the coating film. The present invention allows low-viscosity, low-VOC coatings based on narrow molecular weight distributed polyester polyols containing tertiary acid ester groups, the coatings having sufficiently high Tg for good drying characteristics, physical properties and appearance.